Catchment classification- understanding hydrologic similarity through catchment function

The dissertation presented in this document focuses on understanding the challenges and opportunities for the use of catchment classification to advance hydrologic understanding. The work is broken up into three main components briefly outlined below.;[1] The first portion of this work includes the derivation and identification of key hydrologic characteristics (denoted as "hydrologic signatures", or "signatures") based on the hydrologic behavior of a catchment. These signatures are subsequently used to create a catchment classification system for about 300 US basins. [2] The second part then uses a model-based strategy to catchment classification and to understanding dominant hydrologic controls on these signatures. A top-down modeling framework with model structures of increasing complexity is applied to the same catchments used in part 1. The minimum complexity needed to represent model structures is identified. Catchments requiring similar model complexities are considered hydrologically similar. [3] In the third study, the temporal consistency of a signature-based classification is assessed over a period of over 40 years. This work provides insight into the potential hydrological implications of climate and land use change.;Throughout this thesis we assume that hydrologic similarity is derived from the hydrologic behavior of a catchment. This notion is different from the previous classification strategies focused on physical and climatic characteristics without explicit mapping between these characteristics and the observed or expected hydrologic behavior.